The present invention relates to product packaging, and in particular to a self-sealing valve for fluid products, and the like.
Many different types of packages or containers are presently available for packaging non-solid products of the type which are capable of flowing, such as fluid or fluidized materials, including liquids, pastes, powders, and the like, which substances are collectively and generically referred to herein as “fluids”. Some such packages include a dispenser which permits a selected amount of fluid to be discharged from the package, and then reseals to close the package.
Self-sealing dispensing valves have been used in packaging for certain types of products, such as the container disclosed in U.S. Pat. No. 4,728,006 to Drobish et al, which is designed for shampoos, conditioners, and the like. However, such valves have been known to experience some types of sealing problems, and inconsistent dispensing characteristics, particularly when the packages are exposed to significant temperature variations.
Valves constructed from most conventional plastic materials cannot be used in at least certain types of packages, since they either react with or adulterate the product. For instance, in food packaging, care must be taken to avoid the use of valve materials which might contain any type of toxin. Furthermore, active ingredients in products can cause the valve to either embrittle or soften, thereby ruining the designed flow rate and/or self-sealing characteristics of the valve.
Liquid silicone rubber valves have recently been used in some types of packaging, and have proven particularly advantageous since the material is inherently quite inert, and will therefore not either adulterate or react with the packaged product. Examples of such packaging are provided in applicant's U.S. Pat. No. 5,033,655 to Brown. Although liquid silicone rubber possesses many attributes for use in packaging, it also has other characteristics which render such applications problematic. For example, the surfaces of liquid silicone rubber parts are extremely tacky or sticky, having a very high coefficient of friction. As a result, in attempting to attach a dispensing valve to a container by a conventional threaded collar arrangement, the surfaces of the valve flange will stick tightly to the adjacent surfaces of the container and collar before the collar can be tightened securely enough to create a leak-resistant seal. Tightening of the collar often causes the valve flange, as well as the entire valve to distort from its designed shape, thereby preventing the formation of a secure seal, and/or changing the intended dispensing and sealing characteristics of the valve.
Another drawback associated with the use of liquid silicone rubber in dispensing valves for product packaging is that there is presently no available adhesive capable of connecting the valve to a container in a manner that will withstand the operating pressures to which the valve and container are repeatedly subjected. The unique imperforate nature of the surfaces of the liquid silicone rubber valve precludes the use of conventional adhesives. Hence, the attachment of the liquid silicone rubber valve to a container in a manner that will not leak, and will withstand repeated pressurization and depressurization of the dispensing package is an important consideration.
Another problem experienced with prior dispensing packages relates to achieving a proper design balance between the package container, valve, and fluid product, so that the product can be repeatedly dispensed without requiring excess force, and will neatly discharge only that amount of product which is desired by the user, particularly in keeping with the type of product involved. For instance, when dispensing highly concentrated fluid products, such as hand soaps, and the like, the user will typically require only a small amount or dollop of soap per application to achieve satisfactory results. In contrast, when using other types of fluid products, such as skin moisturizers, tanning formulas, and the like, larger quantities of product are typically required by the user for each application. The ability of the valve to quickly and readily open in response to moderate pressure on the container is important, as is the ability of the valve to quickly and securely close when the pressure has been released. Also important is the amount of pressure which must be maintained on the container to sustain fluid through the valve once the valve is opened. The ability to quickly and accurately achieve a proper balance between all of these factors is very desirable in designing dispensing packages.